MVC4 & IClientValidatable - Automatic AJAX calls to server side validation

Question

I\'m looking to implement custom client side validation in MVC4. I currently have it working well with the standard attributes, such as this in my model

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Answer 1

MVC comes with RemoteAttribute which internally makes an ajax call to a controller method that returns a Json value indicating if validation succeeded or failed

public JsonResult IsValid(string SourceDirectory)
{
  if (someCondition) //test if the value of SourceDirectory is valid
  {
    return Json(true, JsonRequestBehavior.AllowGet); // indicates its valid
  }
  else
  {
    return Json(false, JsonRequestBehavior.AllowGet); // indicates its not valid
    // or return Json("A custom error message that overrides the default message defined in the attribute");
  }
}

and decorate your property with

[Remote("IsValid", "YourController", ErrorMessage = "The path is not valid")]
public string SourceDirectory { get; set; }

Note: The RemoteAttribute is only for client side (jquery unobtrusive validation) and you may still need additional server side validation.

Refer How to: Implement Remote Validation in ASP.NET MVC for a detailed example